Manufacture of seamless tubes



Feb. 6, 1934. w. BARK MANUFACTURE OF SEAMLESS TUBES Filed March 14, 1932 v a 5/ y/fa/wqg/s.

f9wni07" Patented Feb. 6, 1934 UNITED STATES MANUFACTURE OF SEAMLESS TUBES William Bark, Gary, Ind., assignor to National Tube Company, a corporation of New Jersey Application March 14, 1932. Serial No. 598,815 3 Claims. (01. 80-62) This invention relates to the manufacture of seamless ,tubes and more particularly to the hot rolling of seamless tubes, and has for one of its objects the provision of a novel method of rolling seamless tubes which will facilitate the removal of any scale formed on the interior of the tubes and will reduce the formation of scale due to oxidation during the rolling operation.

Another object is to provide a method of rolling whereby the plug over which the tube is rolled is coated with a film of lubricant during the rolling operation which prevents the building up or fusing of quantities of scale and the metal of the tube on the plug, thereby eliminating the tearing of the interior surface of the tube and providing a highly improved product.

In the drawing:

Figure 1 is a planof a seamless tube rolling mill constructed in accordance with this invention.

Figure 2 is a sectional elevation on the line II-II of Figure 1. v

Figure 3 is an enlarged sectional plan showing the detailed construction of the mandrel plug.

Referring more particularly to the drawing, the numeral 2 designates a seamless tube rolling mill having a mandrel bar 3 associated therewith which carries at its free end a mandrel head 4 on which is mounted the usual plug 5 over which the tube being rolled is worked.

The mandrel bar 3 is of hollow construction and has a pipe 6 extending therethrough which terminates at the forward end of the mandrel plug within a hollow nose or nozzle head 7 which is perforated, as at 8. The pipe 6 isconnected at its rear end to any suitable source of gaseous fluid under pressure, such as compressed air, which fluid is delivered into the hollow nozzle head 7 and escapes through the holes or apertures 8 into the interior of the tube being worked.

40 At the forward side of the rolling mill 2 is provided the usual reheating furnace 10 and skid bed 12. The reheated tubes are delivered from the furnace onto the bed 12 and are transferred from the bed 12 onto the incoming trough 13 of 45 the mill. At each side of the bed 12 are provided suitable salt feeding apparatus 14 adapted to project a quantity of sodium chloride or other sodium salt into the interior of the hot tube from each end as it is being transferred over the bed 12.

In carrying out the method of this invention the reheated tubes are provided with a quantity of sodium chloride or other sodium salt from the salt feeding apparatus 14 and the hot tubes are delivered onto the incoming trough 13 and passed into the mill. As the hot tubes pass over the mandrel plug 5 the fluid under pressure, which is preferably compressed air, is projected into the tube and serves to distribute the sodium chloride or other sodium salt through the tube.

The sodium salt, as it is distributed through the 611 hot tube by thecompressed air volatilizes and, due to chemical reactions, serves to break down the scale-formed on the interior of the tube and at the same time fills the tube with the fumes and/or gas which serves to exclude air from the interior of the tube, thereby materially reducing the oxidation of the interior of the tube during the rolling operation.

Due to an unknown chemical reaction, a filmlike coating is formed on the surface of the man- 7 drel plug 5 by the volatilized sodium salt, which coating serves as a lubricant and prevents the sticking or fusing of'the metal of the hot tube and the scale from the interior of the tube onto I the plug, thereby maintaining the smooth surface on the plug and preventing tearing or marring of the interior surface of the hot rolled tube.

The use of sodium chloride or other sodium salts in the manner above described has resulted so in a materially improved product and has enabled the users to roll tubes of materially thinner walls than was possible with any other known method. While the exact chemical reactions taking place within the hot tubes are unknown, the features set forth above have been particularly noted, especially the formation of the lubrieating coating on the mandrel plug which prevents the building up or fusing of metal on the plug. Due to the fact that the plug surface remains smooth at all times the interior surface of the tubes are smooth and of a much higher finish than tubes rolled by any other known method. Experience has also shown that the mandrel plugs may be used for a much longer time, because there is no building up or fusing of scale on the plug surface, and this results in a material saving in both labor and expense.

While I have shown a certain specific embodiment of apparatus for carrying out my invention and have described a certain specific sequence of steps, it will be understood that I do not wish to be limited thereto, since various modifications may be made without departing from the scope of my invention, as defined in the appended claims.

I' claim:

1. The method of hot rolling seamless tubes which consists in depositing a quantity of sodium salt in said tubes and distributing said salt l l0 through the tubes during the rolling operation by gaseous fluid under pressure, said salt volatilizingin the hot tube and serving to loosen the scale and form a coating on the plug over which the tube is being rolled which prevents the metal of the tube fusing to the plug, the gases formed by the volatilizing salt filling the tube, thereby excluding air and materially reducing the oxidation of the tube.

\ 2. The method of hot rolling seamless tubes which consists in depositing a quantity of sodium salt in said. hot tubes immediately prior to rolling said tubes and distributing said salt through the tubes during the rolling operation by compressed air directcd through said tubes, said salt volatilizing in the hot tube and serving to loosen the scale and form a coating on the plug over masses which the tube is being rolled which prevents the metal of the tube fusing to the plug, the gases formed by the volatilizing salt filling the tube, thereby excluding air and materially reducing the oxidation of the tube.

3. The method of hot rolling seamless tubes which consists in depositing a quantity of sodium chloride in said hot tubes immediately prior to rolling said tubes and distributing said sodium chloride through the tubes during the rolling operation by gaseous fluid under pressure, said sodium chloride volatilizing in the hot tube and serving to loosen the scale and form a coating on the plug over which the tube is being rolled which prevents the metal of the tube fusing to the plug.

WILLIAM BARK. 

